#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int n,a,b,c; cin>>n; a=n%10; b=(n%100-a)/10; c=(n%1000-a-b)/100; cout<<a+b+c; return 0; }